Lwt_stream.get blocking

I am getting an object from a stream and timing it like so:

let t1 = Time_now.nanoseconds_since_unix_epoch () in
let* msg_event = Lwt_stream.get s.msgs in
let t2 = Time_now.nanoseconds_since_unix_epoch () in

I also tried this, which had the same behaviour:

let stream_get q =
	try (
		let* e = Lwt_stream.next q in
		Lwt.return_some e
	with Lwt_stream.Empty -> Lwt.return_none

Most of the time this operation takes very little time, but sometimes it will take a long time to return as it appears to be waiting for an element to be added to the stream (in another thread). I want the function to return None immediately if the queue is empty rather than waiting. How can I do this?

I think get_available will work - it is not a blocking operation as shown by the signature.